1. Field of the Invention
This invention relates to coverings for mattresses, and more particularly to sheets with fitted covers in combination with elastic means to aid in maintaining the fit of the corners on the mattress. The invention especially pertains to disposable sheets with their attendant advantages and benefits.
2. Description of the Prior Art
Fitted sheets are well-known. One type consists of sheets which are restrained from moving relative to the mattress only by the fitted corners, as exemplified by Ford et al U.S. Pat. No. 2,695,414. A second type combines fitted corners with elastic means of various kinds to assist holding the sheet in place. An example of this type is Cobb U.S. Pat. No. 3,114,156. A third type consists of those sheets in which the elastic properties of the sheet material itself are used to maintain a proper fit, such as described in May U.S. Pat. No. 2,942,280.
Fitted sheets may also be divided by the method of their manufacture. One group contains those manufactured by cutting the base material into individual blanks of the size and shape required to suit the corner design and then properly attaching the previously cut edges to form the corners. Black U.S. Pat. No. 2,569,627 illustrates a sheet manufactured in this manner. A second group contains sheets which can be fabricated without cutting the sheet material prior to forming the corners. An example is Hrubecky et al U.S. Pat. No. 3,321,782. Sheets made according to the second group are readily adapted to a method of continuous manufacture from rolls of material.
Fitted sheets may be considered as reusable or disposable. Disposable sheets are attractive for use in hospitals and nursing homes. To qualify for disposable use, sheets must be low in cost. They are preferably manufactured by a continuous process, because that process is normally higher in volume and therefore less expensive than manufacturing sheets from individual blanks.
Disposable sheets require the use of inexpensive materials such as paper tissue or nonwoven webs of synthetic polymers such as polypropylene. These materials are comfortable, easy to use, and commercially available in rolls suitable for continuous methods of manufacture. Materials which are inherently elastic are usually too expensive for use as disposable sheet base material.
Corner pockets are readily formed in sheets of tissue or nonwoven polymers by well known methods, which may vary with the particular materials. Unfortunately, these materials, especially the polymers, tend to be slippery when utilized as bed sheets. Even with pockets formed in the four corners, the sheets tend to slide out of position during use.